I admit I didn't patricipate myself...
This is our main problem actually, the lack of permanent connected people...
In fact, that's right when you connect and see there's nobody (or almost), this doesn't encourage to stay connected and to play as it's main goal (and fun) is the cooperative mode... We tried to add the scores (and records) tables to find interest playing in solo mode (waiting for other to connect), and we're looking for other ideas (you're welcome if you have any )...
We're convinced the concept could be fun, but don't know how to make a solid community to ensure there's always connected people...